The Happy Isles of Oceania: Paddling the Pacific (New York: Putnam, 1992), chapter 1:
“I’ve been all over the Pacific,” the man next to me said. He was from California. His name was Hap. “Bora-Bora. Moora-Moora. Tora-Tora. Fuji.”
“Fiji,” his wife said.
“And Haiti,” he told me.
“Tahiti,” his wife said, correcting him again.
“Oh God,” he said, “Johnston Island.”
“What was that like?”
This sinister little island, with the Stars and Stripes flying over it, is 800 miles west of Honolulu, and was formerly a launching site for H-bombs. More recently, nuclear waste was stored there, along with nerve gas and stacks of hydrogen bombs. A recent accident had left one end of Johnston Island radioactive.* Few Americans have heard of it. The anti-nuclear New Zealanders can tell you where it is and why it terrifies them.
“Who said I got off the plane?” Hap said.
“We’re members of the Century Club,” his wife said. “You can only join if you’ve been to a hundred countries.”
“What does ‘been to’ mean? Pass through the airport? Spend a night? Get diarrhea there?”
“Guess he’s not a member!” Hap said, joyously.
Tourists don’t know where they’ve been, I thought. Travellers don’t know where they’re going.
(This was easy to find using Google Books search, which I commend to you.)
* Is Theroux referring to the Bluegill Prime accident, in which a nuclear-armed PGM-17 Thor ballistic missile exploded on the launch platform? This accident was in July 1962 and so hardly ‘recent’ in 1992 but Cold War secrecy probably made it hard for Theroux to check the date.